Although the influences of tricyclic antidepressant drugs on noradrenergic mechanisms have been studied in detail, relatively little is known about the net effect of these influences combined. The ongoing research in my laboratory studies this net effect by examining the firing and responsiveness of noradrenergic postsynaptic cells using neurophysiological techniques. The proposed research is to continue this line of investigation by comparing the net effect produced by different antidepressant treatments, examining the net effect of the same antidepressant drugs on different noradrenergic systems, and by determining the response of noradrenergic postsynaptic cells to a number of stimuli. It is expected that the results will provide information about the net effect of antidepressant treatments on the overall functioning of central noradrenergic systems.